The present invention relates to a tape reel assembly for a data storage tape cartridge. More particularly, it relates to a tape reel assembly including a self-adjusting flange component configured to limit lateral movement of storage tape otherwise wound about the tape reel.
Data storage tape cartridges have been used for decades in the computer, audio, and video fields. The data storage tape cartridge continues to be an extremely popular device for recording large volumes of information for subsequent retrieval and use.
A data storage tape cartridge generally consists of an outer shell or housing maintaining at least one tape reel assembly and a length of magnetic storage tape. The storage tape is wrapped about a hub portion of the tape reel assembly and is driven through a defined tape path by a driving system. The housing normally includes a separate cover and base, the combination of which forms an opening (or window) at a forward portion thereof for allowing access to the storage tape by a read/write head of a tape drive. This interaction between storage tape and head may take place within the housing (for example, with a mid-tape load design), or the storage tape may be directed away from the housing to an adjacent area at which the read/write head is located (for example, with a helical drive design or a leader block design). Where the tape cartridge/drive system is designed to direct the storage tape away from the housing, the data storage tape cartridge normally includes a single tape reel assembly. Conversely, where the tape cartridge/drive system is designed to provide head/storage tape interaction within or very near the housing, a two- or dual-tape reel assembly configuration is typically employed.
Regardless of the number of tape reel assemblies associated with a particular data storage tape cartridge, the tape reel assembly itself is generally comprised of three basic components; namely, an upper flange, a lower flange, and a hub. The hub forms an outer, tape-winding surface about which the storage tape is wound. The flanges are disposed at opposite ends of the hub, and are spaced to approximate the height of the storage tape. To ensure that the storage tape does not undesirably contact one of the flanges during a winding operation, the designed flange-to-flange spacing is normally slightly greater than a height of the tape. As a point of reference, unexpected contact between a flange and an edge of the tape in a once around pattern will reflex a high frequency lateral movement back to the read/write head, possibly leading to servo-tracking errors. In this regard, tape reel flanges are typically injection molded plastic components. Though cost effective, this manufacturing technique invariably results in a small amount of flange warp. This warpage, in turn, renders consistent, precise flange-to-flange spacing difficult to achieve, especially at the outer edge of the flange. As such, a well-accepted design technique is to outwardly taper an inner surface of the flange (relative to radial extension from the hub upon final assembly), thereby providing an increasing flange-to-flange spacing from the hub to an outer edge of each flange. The designed taper virtually eliminates the possibility that any unexpected deviation in the flange orientation (due to warpage) will result in potentially detrimental contact between the flange and the lateral tape edge during winding.
While the above-described flange design has proven highly successful in eliminating undesirable flange-tape edge contact (and the resulting high frequency lateral movement problems described above), other concerns have been identified. In particular, as the storage tape is wound about the hub, consecutive wound layers of tape are relatively unstable due to several layers of tape floating on a layer of air. The storage tape generally settles in against one of the flanges as a result of the bipolar energy profile in the storage tape. The air slowly leaks out from the adjacent layers of tape, but until the adjacent layers come into contact with one another, the side-to-side energy in the tape path determines which flange the tape will ultimately settle against. The low mass storage tape can shift in the lateral direction very quickly while it is winding about the hub. In fact, the storage tape may shift back and forth between the inner surface profile of the upper and lower flanges (sometimes referred to as xe2x80x9cpack shiftxe2x80x9d). Due to the tapered inner surface flange profile described above, then, the storage tape may experience a discernable lateral shift as additional tape is continuously wound onto the tape reel assembly.
Previously, the lateral storage tape displacement identified above was of minimal concern as the servo-track associated with the storage tape was sufficiently sized to account for expected lateral displacement. In general terms, the servo-track provides a baseline by which the read/write head can ascertain a xe2x80x9cpositionxe2x80x9d of the storage tape itself. The servo-track width has heretofore been sufficient to accommodate the lateral movement associated with the tapered inner surface flange design. However, evolution of tape cartridge/tape drive technology has resulted in increasingly smaller track widths for enhanced storage space, including the servo-track. The reduced-width servo-track has a limited frequency (or lateral displacement) response. Unfortunately, the above-described tapered flange-induced tape path deviations may entail a frequency well above the bandwidth of the now smaller sized servo-track. This, in turn, can lead to servo-tracking errors.
It may be possible to address the above concern by utilizing different materials for the tape reel flanges and/or a more precise manufacturing technique. However, this approach would greatly increase the overall costs of the cartridge itself, and is thus not a feasible solution from a manufacturing standpoint. Alternatively, a pack arm roller can be incorporated into the cartridge that serves to squeeze air out from between tape layers as the tape is being wound onto the tape reel. Unfortunately, current cartridge layouts do not provide sufficient space for a pack roller, and interaction with the pack roller may, in fact, contribute to lateral tape movement. Including a separate pack roller would increase overall cartridge costs. Similarly, it may be possible to incorporate a belt into the cartridge design that would otherwise contact the tape as it is being wound onto the tape reel assembly, again forcing air out from between layers of tape. The belt itself can, however, contribute to tape distortion, and again would overtly increase overall cartridge costs.
Data storage tape cartridges continue to be important tools used to store vast amounts of information. While improvements in storage tape media and read/write head technology have greatly increased the amount of data that can be stored by a particular cartridge, previously acceptable tapered flange-related lateral tape movement may no longer be tolerable. Therefore, a need exists for a tape reel assembly configured to control a lateral position of the storage tape as it is wound about the hub that does not grossly affect overall costs.
One aspect of the present invention relates to a tape reel assembly for a data storage tape cartridge. The tape reel assembly includes a hub, a first flange, and a second flange. The hub defines a hub axis, and opposing first and second ends. The first flange extends from the first end of the hub and includes a main body and an adjustment section. The main body extends radially from the hub. The adjustment section is provided within the main body. In this regard, the adjustment section defines a tape edge contact surface and is further characterized by an increased flexibility as compared to the main body. With this construction, the tape edge contact surface is readily deflectable relative to the hub axis. Along these same lines, the adjustment section is configured such that a deflection orientation of the tape edge contact surface is a function of a pressure on the hub. Finally, the second flange extends from the second end of the hub. During use, as pressure on the hub increases (e.g., due to an increased length of tape wrapped around the hub), the adjustment section will deflect. This deflection, in turn, positions the tape edge contact surface to desirably direct the storage tape, that is otherwise being wound about the hub, to a consistent lateral position relative to the hub axis. In one preferred embodiment, the adjustment section includes an elongated, tubular member extending from a fixed end, that is otherwise associated with the hub, to free end located opposite the hub.
Another aspect of the present invention relates to a data storage tape cartridge including a housing, at least one tape reel assembly, and a storage tape. The housing defines an enclosed region. The tape reel assembly is rotatably disposed within the enclosed region and includes a hub, a first flange, and a second flange. The hub defines a hub axis, a tape-receiving surface, and opposing first and second ends. The first flange extends from the first end of the hub and includes a main body and an adjustment section. The main body extends radially from the hub. The adjustment section is provided within the main body and defines a tape edge contact surface. Further, the adjustment section is characterized by an increased flexibility as compared to the main body, such that the tape edge contact surface is readily deflectable relative to the hub axis. The second flange extends from the second end of the hub. Finally, the storage tape is wound about the tape-receiving surface of the hub. With this construction in mind, winding of the storage tape about the hub imparts a winding pressure onto the hub itself. In this regard, the adjustment section is configured such that a deflection orientation of the tape edge contact surface is a function of the winding pressure. During use, as the winding pressure increases, the adjustment section will deflect to place the tape edge contact surface into contact with a lateral edge of the storage tape. Thus, a position of the storage tape relative to the hub axis is dictated by the adjustment section, as opposed to the main body. For example, and in one preferred embodiment, a radial extension of the main body from the hub defines a tape guide plane. With this construction, the adjustment section is configured such that with increased winding pressure, an area of the tape edge contact surface that is otherwise below the tape guide plane increases for contacting an edge of the storage tape. In another preferred embodiment, both of the first and second flanges include an adjustment section as described above.
Yet another aspect of the present invention relates to a data storage tape cartridge including a housing, at least one tape reel, and a storage tape. The housing defines an enclosed region. The tape reel is rotatably disposed within the enclosed region and includes a hub, a first flange, and a second flange. The hub defines a hub axis, a tape-receiving surface, and opposing first and second ends. The first flange extends from the first end of the hub and includes a main body and an adjustment section. The main body extends radially from the hub. The adjustment section is provided within the main body, and defines a tape edge contact surface. Further, the adjustment section is characterized by an increased flexibility as compared to the main body, such that the tape edge contact surface is readily deflectable relative to the hub axis. The second flange extends from the second end of the hub. Finally, the storage tape is wound about the tape-receiving surface of the hub. With this construction, the adjustment section is configured to gradually deflect inwardly relative to the hub axis as a length of the storage tape wound about the hub is increased, such that the tape edge contact surface contacts an edge of the tape and establishes a lateral spacing between the tape edge and at least a portion of the main body.